Conventionally, in a CMOS image sensor, fixed-pattern noise (FPN) might be generated in a captured image due to variation in threshold among metal-oxide-semiconductor field-effect transistors (MOSFETs) used in circuits of pixel cells.
Recently, methods of inhibiting such variation in the threshold are considered (refer to, for example, Patent Documents 1 to 5 and Non-Patent Document 1). In such methods, voltage of a floating diffusion (FD) is controlled by negative feedback for each pixel such that a pixel output is constant.